Well completion apparatus



Nov. 21, 1950 T. A. HUBER 2,530,966

WELL COMPLETION APPARATUS Filed April 17, 1945 55- E 34 i H gn'ugl 1 f1'1 U 6 nu m, H M

I: :5 9M 4'. INVENTOR.

Patented Nov. 21, 1950 WELL COMPLETION APPARATUS Theodore A. Huber,Houston, Tex., assignor to Standard Oil Development Company, acorporation of Delaware Application April 1'7, 1943, Serial No. 483,407

1 Claim.

1 v The present invention is directed to apparatus for completing orworking over oil and gas wells,

particularly those which produce under high pressure.

' The principal object of the present invention is the provision ofapparatus for the completion of wells drilled for oil and gas whichmakes possible the bringing of the well into production withoutsubjecting the perforations or drainage openings into the producinformation to a head of fluid having a higher hydrostatic pressure thanthe formation pressure and containing solids that can plug suchopenings.

Another object of the present invention is the provision of apparatusfor completing a Well which enable the operator to prepare his well forproduction completely before the producing formation is tapped, thisoperation being made the last operation in the completion process. Anadditional object of the present invention is the provision of means forcompleting oil and gas wells after th setting of easin which will permitremoval of drilling and pipe handling equipment from the well locationbefore the ordinary waiting time for cement setting has elapsed prior toperforating the casing and formation for production.

Further objects and advantages of the present invention will appear fromthe following detailed description of the accompanying drawing in which-Figure 1 is a vertical section through a well completed in accordancewith the present invention with the completion apparatus in place;

Figure 2 is a detail, in vertical section, of the gun perforator-screencombination constituting one feature of the present invention; and

Figure 3 is another detail, in vertical section, of the device used toactuate the gun.

Fig. 4 is a horizontal sectional view on IVIV of Fig. 3.

Referring to the drawing in detail, numeral 1 designates a boreholedrilled into or through a formation containing oil or gas the top ofwhich is indicated at 3. In the practice of one embodiment of thepresent invention the borehole is drilled through the producingformation and then casing 4, provided with a float shoe 5, such as thatillustrated on page 227 of the 1942 Com- L log, including a casinghanger, a tubin hanger, and a Christmas tree, the latter being indicatedas awhole by numeral 8. Suspended from the tubing hanger is string 9 oftubing carrying at its lower end a screen It provided with slots II anda back-pressure valve l2. Any conventional type of screen may beemployed, including those which are referred to as prepacked liners, asillustrated, for example, at page 1420 of the 1942 Composite Catalog.

In adapting the screen for use in the practice of the present invention,however, there are inserted inside the screen a number of gun barrels13. Each gun barrel is a cylinder having a closed end set in a socket I4screwed into the wall of the screen and having an open end screwed intothe opposite wall of the screen. The closed end of the barrelconstitutes a powder chamber 15 ahead of which is arranged a bullet It.The powder chamber is provided with a firing filament H, the variousfilaments being connected in series or in parallel, as desired, to aconductor I8 soldered or otherwise connected to a metal contact 19. Eachfiring filament is also grounded to its gun barrel. It will beunderstood that electrical devices for spacing the occurrence of theshots may be arranged in the firing circuit. Likewise, the firingfilaments may be connected to a firing device operated by a go-devil ina manner known in the art.

If desired, the screen may be provided at its top with a suitable packer28, such, for example, as the packer shown at page 2291 of the 1942Composite Catalog, or other numerous packers illustrated in thiscatalog. Also, if desired, a safety joint may be added to the assemblyabove the screen, which will permit releasing the tubing with awell-completion assembly 1, such as that shown at page 1589 of the 1942Composite Catafrom the screen. Such a safety joint is illustrated in the1942 Composite Catalog on page 2296-.

The tubing in this case is provided with a separate section 21!, ontothe lower end of which the screen is screwed. This lower end is flaredoutwardly and is provided with internal screw threads 22 into which isinserted a plug composed of a metal cup 23 carryin inwardly directedcircumferentially-spaced arms 24 of Bakelite or similar material, inwhich is fixed the metal contact 19 which, in the embodiment shown, hasaconical shape. The space between the arms 24 permits the flow of fluiddown through the tubing to the screen. The metal cup 23 has an inwardlydirected flange 25 for the purpose hereinafter indicated.

In the arrangement shown, the power necessary to fire the gun issupplied by a magazine of batteries composed of a cylindrical chamber 26having at one end a metal plug 21 and at the other end a plug 28 ofinsulating material, such as Bakelite, having a metallic tip 29connected to a button 30 on the inner face of the plug by a conductor31. The assembly is suspended on a wire line 32, which may be introducedinto the tubing through a lubricator 33 arranged at the top of theChristmas tree. This lubricator is of a type well known in the art, suchas that illustrated on page 970 of the 1942 Composite Catalog as Unit 5.With this type of lubricator it is possible to introduce into or removefrom the production tubing, under formation pressure, any device ofsuitable size without releasing the pressure inside the tubing. It willbe understood that when a go-devil type firing mechanism is em ployedthe go-devil will take the place of the cylinder 26. It may be mentionedhere also that the cylinder 26, instead of being a container forbatteries, can be merely a weight constituting one terminal of a sourceof power, such as a generator, arranged at the surface. The circuit ofthe generator can be kept closed until this terminal makes contact withthe metal contact I9 at the bottom of the tubing. It will be observed inthe embodiment shown that the cylinder 25 is metallic and serves toclose the battery circuit when tip '29 and contact is are engaged byvirtue of its engagement with flange 25. It will be understood thatflange 25 may be provided with suitable circumferentially spaced slotsto permit the passage of fluid.

In the practice of the present invention, the casing is first set at apoint opposite the producing formation and cemented in place. In theembodiment shown the cementing was performed with the float in the shoeat bottom, in which case, when all of the cement is in place as shown,there is nothing above the guide shoe requiring drilling. In a differenttype of cementing operation there may be a column of cement in thecasing to be drilled out after the cementing operation is completed. Inany case, any loose solids are washed out of the casing, leaving in itonly clear fluid. Preferably this fluid should be lighter than drillingfluid, a light oil or clear water being suitable. There are twoobjectives in using such a fluid. The first is that when the casingopposite the producing formation is perforated it is detrimental to havea heavy fluid, such as mud, in the casing because it will run into theperforations and contaminate the formation and, what is more serious,plug up the perforations. Such plugged perforations are a hindrance toproper drainage of the reservoir and they result in flow beingconcentrated at the one or two openings that may be cleaned throughordinary cleaning operations to put wells on production; theconcentrated flow results in costly damage to well screening equipment.Furthermore, it is desirable to bring the well into production as soonas the casing is perforated and this cant be done if there is in thecasing or in the producing string a fluid having a hydrostatic headgreater than the formation pressure.

The second objective in replacing dirty fluid in the casing is to makepossible the setting of screen without having the perforations in thescreen plugged up during setting or producing operations with solidssuspended in the fluid in the casing. In former types of wellcompletions the setting of screen, especially where the screen includesa prepacked liner, in such a manner as 4 to have the screen or the lineroperate efliciently. has been a serious problem by virtue of theuniversal practice, dictated by necessity, of having a, head of drillingmud in the casing when the casing is perforated so as to keep the wellunder control. In the completion operation of the present invention, inwhich the screen is placed before the perforation is effected, thenecessity for using drilling mud or other heavy fluid in the casing iseliminated. Accordingly, the problem of fouling the screen or prepackedliner, as the case may be, is avoided.

With the casing free of all fluid except clean, preferably light, fluid,the casing head, together with the tubing hanger and string of tubingwith its attached screen, is installed. Packer 20, when employed, isset, and the lubrlcator 33 is installed on the Christmas tree. Then,suhicient setting time for the cement having been allowed, the magazine26 is lowered on a wire line through the lubricator to lire the gunbarrels. In the embodlment shown, the screen contains six gun barrels.It will be understood that this number can be increased or decreased andtheir position changed as deslred. In Figure l, numeral 34 designatesthe path taken by the bullets. As soon as the perforating is completed,the magazine is withdrawn from the tubing and the Well is placed onproduction. By reason of the fact that a light nuld may be employed inthis completion operation, the necesslty for swabbing and pipe handlingis eliminated. Therefore, according to the present invention, as soon asthe casing is set, the tubing and screen hung, and the well headequipment installed, the drilling equipment and all pipe handlingequipment can be moved to a new location, resulting in a, considerablesaving in time and expense.

In the foregoing description reference has been made to the replacementof heavy fluid in the well by a light fluid, the hydrostatic head ofwhich is less than formation pressure. This is a particular feature ofthepresent invention which is not necessarily confined in its practiceto the specific embodiment described herein. It is applicable towork-over jobs and to testing operations, as well as to originalcompletions. As is well understood, a work-over job ordinarily involvesthe killing of the well by the introduction or accumulation of a heavyfluid followed by operations such as the packing off of the formation tobe worked upon, which operation involves the removal of the producingstring, in some cases a squeeze cementing job, and usually a perforatingjob. These operations are expensive and time consuming, requiring alsothe presence on the location of the derrick structure. According to thepresent invention, such a job is simplifled, especially where anopen-ended producing string is employed, merely by first killing thewell, then performing such operations as are required, as for example,squeezing cement into the formation to be worked, followed by removal ofexcess cement. Next, the heavy fluid in the well is replaced by a lightfluid, such as, for example, oil, well head equipment is installed, anda perforating gun is introduced into the tubing through a suitablelubricator and spotted opposite the formation to be perforated.Perforation is then effected, the gun withdrawn, and the well placed onproduction. As will be clear, this procedure eliminates many of theexpensive operations hitherto required to achieve this purpose.

The nature and objects of the present invention having been thusdescribed and illustrated,

5 what is claimed as new and useful and is desired to be secured byLetters Patent is:

A screen for an oil well carrying a plurality of laterally disposed gunbarrels each adapted to discharge a bullet from its outer end laterallyfrom said screen and each containing a firing chamber, the inner end ofeach barrel being sealed whereby the firing of the bullet does not leavean opening for the entry of sand and debris into said screen, a bulletin each barrel arranged for projection outwardly ahead of said firingchamber, a firing filament in each of said firing chambers, means forconnecting said screen to a string of tubing, and an electrical contactcarried by the upper end of said screen, electrically connected to eachof said firing filaments and arranged for contact with an electricalterminal lowered through said tubing.

THEODORE A. HUBER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATliINTS Number Name Date 2,016,919 Church Oct. 8, 19352,029,490 Lane Feb. 4, 1936 2,082,329 Foran et a1 June 1, 1937 2,157,729Church May 9, 1939 2,211,206 Howard Aug. 13, 1940 2,226,073 Ricou Dec.24, 1940

